I'm hoping with automatic vehicles and tunneling this mass transit versus not mass transit dichotomy will just fade away. Automatic buses and cars could use the same tunnel. Just make sure the tunnel does not clog up by charging each vehicle by how much space it uses up. People are willing to pay for transportation, many just don't like paying for other peoples transportation.

With enough tunnels traffic congestion disappears. Unless for some reason you think people should just not be able to move around when they want to, this would be great.